The present invention relates to the cooling of the walls of shaft furnaces and more particularly, but not exclusively, to the cooling of the refractory walls of blast furnaces.
In the conventional constructions, the shafts and the boshes of blast furnaces are equipped with cooling boxes and/or trickle boxes. These boxes are intended to cool the brickwork and at the same time to support it. In the boshes, where the stability of the refractory material is assured, it may suffice to use a trickle system, but the boxes also enhance the service-life of the refractory materials. However, the use of such boxes involves the inconvenience that the noses of the boxes, deeply buried in the refractory material, are very soon subjected to abrasion by the downcoming charge and the upgoing stream of hot dust-laden gases because of the wear suffered by the refractory material. This results in a considerable number of boxes being used up.
The double-wall (water-jacket) technique has been developed for the purpose of effecting efficient cooling of the boshes and the bottom of the shaft. In this system, the local cooling effected by the boxes is replaced by cooling over the entire surface of the refractory material. The results achieved by the use of this technique have still not been satisfactory, so that use has been made of a combination of the double-wall system and the arrangement using cooling boxes. This process is however of limited application, since the heat-flow causes stresses in the sheet-metal parts of the installation.
For these reasons, it has been necessary to turn to the idea of effecting internal cooling in the most uniform manner possible. Therefore, in various countries internal cooling means have been designed which have consisted of a cast-iron plate in which were embedded steel tubes through which a stream of water was passed. These cooling means do not appear to have been completely satisfactory. In particular the plate becomes deformed, i.e., curved when heating takes place. The effect of this is to push out the refractory material, and this, on the one hand, breaks up the brickwork and, on the other, reduces cooling efficiency since the required contact between the cooling means and the wall to be cooled no longer exists.